the sudden motion sensor detects excessive motion and swings the arm off the HDD platters to protect data. This clip shows a slight tap on the screen (which wouldn't even set off the sensor) and running a script of some form. This is not what the motion sensor does.
EDIT: i am wrong! I read a bit more into it and SMS picks up any vibrations, even very small ones. just hitting my table softly sets it off. i probably should learn to read into stuff more before i dismiss it.